Re: Herbivore protection

[Stanley Friesen <sarima@ix.netcom.com>]

At 02:28 PM 6/8/97 -0400, John Bois wrote:
>  I mean P. pigeons almost certainly
>would not choose nesting sites, initially, at random.  I bet they are
>operating under some optimizing regimes.

I basically agree here.  But optimizing *what*?

For mass nesting there must be sufficient suitable nesting spots in the
colony area.  And there must be sufficient forage available in the vicinity
of the nesting colony to feed both the adults *and* the rapidly growing
chicks.

It is quite conceivable that the above factors far outweighed predator
density as choice factors.  Iy is also possible that the historically
observed nesting sites were maintained due to what amounts to tradition.
That is they were chosen *long* ago for reasons now lost in history, and
the condition during historical times was irrelevant to the choice.

>  My guess would be this: normally
>they are open-field foragers. 

That seems unlikely to me in an eastern coastal plain bird.  That whole
area was originally heavily forested.  I do not see how an open field
forager could have come to be so hugely abundant in that biome.

>Trees afford more protection than fields.  This is especially true if 
>you
>are the prey of a swift diving bird.

Accipiters and falcons are *specialized* for swooping on their prey in
forest situations. Tree offer precious little protection from such birds.

>... Territoriality would be expected only in a
>place where there is something worth defending.

Mates are the main protected resource in modern territorial species.

>  If all of your food has
>gone off to some remote site there is no point defending anything.

Who said *all* the food left!  Just the big game.  There would still be
pachycephalosaurs and protoceratopsids and probably _Thescelosaurus_.

--------------
May the peace of God be with you.         sarima@ix.netcom.com
                                          sfriesen@netlock.com